The present invention relates to the field of thrust-producing rotors for both model and full-size helicopters. More particularly, the present invention relates to high lift rotors for all types of helicopters and to simple and inexpensive rotors for use in model helicopter applications.
Helicopters are flying machines with the ability to hover and fly forwards, backwards, and sideways. This agility stems from the multiple capabilities of the main rotor system. Since the invention of helicopters in the 1930's considerable effort has been expended advancing helicopter technology, with a substantial percentage of that effort concentrated on the main rotor system.
While the technology of full-size helicopters progressed, model helicopters remained impractical for decades for lack of suitable engines, radio control equipment, and construction materials. As the state-of-the-art in full-size helicopters advanced in the 1950's and 1960's, many novel model helicopter designs were developed, but none proved practical. Model helicopter designers often copied the designs of full-size helicopters without understanding the basic differences between full-size and model aircraft. As a result, scaled-down model helicopters were typically unstable and underpowered.
While mechanically similar, the aerodynamics, operational speeds, and weights of model helicopters are vastly different from those of their full-size counterparts. Model helicopter rotors operate within a low speed range where aerodynamic drag due to the thickness of the rotor blade airfoil becomes very important. Early attempts to utilize the thick airfoils used on full-size helicopters failed in part because engines then available could not overcome the high drag of the rotor blades.
In the 1970's hobbyists developed the first practical model helicopters. Lighter radio control equipment, more powerful engines, and systematic engineering all contributed to early successes. Much of model helicopter design, however, is rooted in tradition. Even though helicopter technology has advanced considerably since that time, the designs and design philosophies of that era are still in widespread use. With an better understanding of small-scale aerodynamics and kinematics, it is possible to devise a model helicopter rotor with capabilities beyond those currently available. Certain aspects of the rotor can benefit full-scale aircraft.
Because the main rotor system of a helicopter is capable of performing so many flight functions, it is usually very mechanically complex. Model helicopters currently available contain myriad pushrods, mixing arms, ball joints, and expensive ball bearings. Swashplate assemblies for controlling the main rotor often utilize specialty ball bearing units which drive the cost up further.
Considering the cost, complexity and lifting capabilities of modern rotor systems, what is needed is a high lift rotor system that is relatively simple, inexpensive, and easy to manufacture.
One object of the present invention is to provide a high-lift rotor system for full-size and model helicopters.
Another object of the present invention is to provide a simple inexpensive rotor system for use on model helicopters.
Generally speaking there is provided herein a main rotor system for a helicopter. Such device is generally mounted to a helicopter and provides a controllable motive force for lifting the helicopter into the air and propelling the helicopter in any direction.
More specifically, the rotor system includes rotor blades and subrotor blades for producing aerodynamic lift. These subrotor blades also act to augment control and stability of the rotor. The rotor system also includes a swashplate assembly and linkage means for transmitting pilot control commands to the rotating rotor blades.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.